Scalable electrode flow field for water electrolyzer and method for rapidly producing it

Abstract

The present disclosure provides approaches for increasing the adhesion of catalyst inks on substrates, the use of binders in the electrode ink to improve coating uniformity, incorporating pore formers in the electrode ink, approaches for growing electrodes on reinforcement layers, increasing electrochemically active surface area, and incorporating specific materials in the electrode ink. The present disclosure also relates to electrodes for electrochemical cells, including area scalable electrodes designed for rapid manufacturing. The materials, devices, and methods described herein may be applied to either or both anode or cathode electrodes for electrochemical cells.

Description

[Technical Field]

[0001] Incorporation by reference to related applications This application claims priority under 35 U.S.SC § 119(e) to U.S. Provisional Application No. 63 / 299,643, filed on 14 January 2022, and all its contents are incorporated herein by general reference.

[0002] Government support Some embodiments of the subject matter of this application were made with the support of the U.S. Government under ARPA-E Award No. DE-AR0001487. The U.S. Government has certain rights with respect to the subject matter of this application.

[0003] Field of Invention This disclosure relates to approaches for increasing the adhesion of catalyst inks to a substrate, the use of binders in electrode inks to improve coating uniformity, the incorporation of porosity-forming agents into electrode inks, approaches for growing electrodes on reinforcing layers, increasing electrochemically active surface area, and incorporating specific materials into electrode inks. This disclosure also relates to electrodes for electrochemical cells, including area-expandable electrodes designed for rapid manufacturing. The materials, devices, and methods described herein may be applied to either or both anode electrodes or cathode electrodes for electrochemical cells. [Background technology]

[0004] An electrochemical cell is a device that can use electricity to induce a chemical reaction or generate electricity from a chemical reaction. When electricity is the output, the cell can be considered a fuel cell or an expander cell, depending on the chemical product. When electricity is the input, the cell can be considered an electrolytic cell, a compressor cell, or a purifier cell, depending on the chemical product. For example, an electrolytic cell takes in electrical energy and stores it in a fuel such as hydrogen by breaking down water into its components. In contrast, a fuel cell is an electrolytic cell that operates in the opposite direction, with hydrogen and oxygen supplied to the cell, which then combines these elements to form water, releasing electrical energy during the process. The basic elements of these devices are two electrodes, an ion-conducting electrolyte, and an ion-permeable layer separating the two electrodes. In the case of a solid electrolytic cell, the ion-conducting electrolyte and separator may be combined into an integrated solid ion-conducting membrane. A complete electrochemical cell may also include a flow field for delivering reactants to electrodes, seals for isolating reactants from each other and from the environment, and one or more impermeable separator plates, also called bipolar plates, for isolating one cell from adjacent cells in a stack and, in one embodiment, for housing a separate cooling fluid for thermal management of the cell.

[0005] Various electrolytes can be used in electrochemical cells, including proton exchange membranes, anion exchange membranes, solid oxide ceramic membranes, and liquid alkaline solutions such as potassium hydroxide and sodium hydroxide. Different electrolytes require different operating conditions, and each has its own advantages and limitations. Advantages of proton exchange membrane electrolytes and anion exchange membrane electrolytes include relatively low operating temperatures and the ability to construct cells using unitized layers of electrolyte / membrane. Electrolytes using such membranes have a clear advantage over other electrolytic cells that can operate using pure liquid water rather than caustic solutions or steam as feedstock, thereby significantly simplifying the system balance.

[0006] As societal efforts to address global climate change accelerate, the need to deeply decarbonize all human energy use has become clear and urgent. Using hydrogen as a carbon-free energy carrier is essential to reaching certain human-industrial sectors where direct decarbonization with electricity is difficult or impossible. Examples of such sectors include steel production, fertilizer manufacturing, and heavy-duty transportation such as truck, sea, and air transport. In addition to these sectors, hydrogen's energy density and stable storage properties make it the most promising candidate for seasonal-scale energy storage, leading to the establishment of grid resilience that uses only renewable electricity. This will be necessary to completely transform energy use to carbon-free sources. These and other advantages have attracted a high level of interest in the production of “green hydrogen.” Hydrogen is given the “green” label if it is produced by electrolysis from renewable electricity (wind, solar, hydro, etc.). The scale required to meet the potential demand for green hydrogen in the future global energy system is enormous. Electrolyzer production capacity needs to increase by orders of magnitude in the next decade to meet such demand, and their costs need to decrease by more than tenfold. Until now, the manufacture of hydrogen electrolyzers has been a niche industry with small systems and limited deployment, based on cells and stacks designed for research and development. Little consideration has been given to the manufacturing speed required to produce and assemble cells and stacks at a pace that meets the ultimate societal need. [Overview of the project]

[0007] One objective of this disclosure is to overcome the limitations of current electrochemical cell designs by approaches to increase the adhesion of catalyst inks to substrates, using binders in electrode inks to improve coating uniformity, incorporating porosity-forming agents into electrode inks, approaches to grow electrodes on reinforcing layers, increasing the electrochemically active surface area, and incorporating specific materials into electrode inks.

[0008] Another objective of this disclosure is to overcome the limitations of current electrochemical cell designs by providing area-scalable electrodes that enable high-speed manufacturing while minimizing capital costs for producing a wide range of electrolytic cell and stack sizes.

[0009] The basic process of water electrolysis involves supplying water to a positively charged anode electrode and conducting ions between the anode and a negatively charged cathode electrode. Oxygen is produced at the anode and hydrogen at the cathode. The specific ions used in this method are the function of the selected electrolyte. In acidic cells, positively charged hydronium ions are conducted from the anode to the cathode. In alkaline cells, negatively charged hydroxide ions are conducted from the cathode to the anode. In both systems, the entire reaction is the same: (2)H2O(l) → (2)H2(g) + O2(g). Electricity must be supplied to drive the reaction. The open-circuit or thermally neutral voltage for the basic reaction of hydrogen to liquid water is 1.481V, and therefore, to allow the reaction to proceed, a voltage higher than 1.481V must be applied to the hydrogen electrolysis cell supplied with liquid water. The size of the cell (i.e., the active area) determines the rate of hydrogen / oxygen production from one cell at a given applied voltage. The total current required for a given applied voltage can be proportional to the cell size (i.e., the active area). In real-world systems, multiple cells can be "stacked" on top of each other to increase production capacity. This cell stacking necessitates applying higher voltages (integer multiples of the number of cells) to drive the reaction. For example, 1000 cm² 2 The single cell is 500cm 2 It can generate the same hydrogen flow as two stack cells, but at 500cm 2 The stack requires inputs of twice the voltage and 0.5 times the current. Flexibility in selecting the required voltage and current can be an important consideration in the design and cost of a total electrolytic system. For example, power supplies for higher current and lower voltage may be more expensive than those for higher voltage and lower current due to the size of the conductors required and the additional materials needed for their configuration.

[0010] As the reaction progresses, water is consumed and a gas of hydrogen + oxygen is produced; therefore, water must be continuously supplied to the cell to sustain the reaction. Stoichiometry is a term relating to the "balance" of a chemical reaction. In an electrochemical cell, the term "stoichiometry" or "stoich" refers to the ratio of reactants supplied to the cell to the amount necessary to precisely balance the entire reaction. For example, an electrolytic cell operating with 2 water stoichs has twice the amount of water as its input required to produce the hydrogen and oxygen leaving the cell. If we conserve the mass of the system with 1 stoich, we can see that the production of 1 kg of hydrogen per hour is related to the production of approximately 8 kg of oxygen per hour and the consumption of approximately 9 kg of water per hour. Electrolytic cells can typically be operated with a minimum water stoich greater than 1 to ensure the appropriate reactants at any point in the cell. For example, when the water flow stoich is 1, all the water supplied to the cell is converted to oxygen at the anode, and the oxygen fraction at the cell outlet is 100% (i.e., no water leaves the cell). This condition can be unstable and may lead to damage due to anode deficiency in the cell near the outlet. Furthermore, since everything exiting the cell is in the gas phase, it can result in high fluid velocity and pressure loss at the outlet. Therefore, process conditions can be selected to maintain the oxygen vapor fraction at the cell outlet below a given threshold. For example, an outlet oxygen fraction of less than 40% can increase the flow field velocity from the water inlet to the outlet by less than twofold. Maintaining an oxygen fraction below 40% may require more than 100 water stoichiometry units.

[0011] The electrolysis process is not 100% efficient, and as a result, some of the input electricity is converted into heat within the cell instead of being stored as chemical energy in the form of hydrogen. This results in a voltage higher than the thermal neutral voltage (1.481V) required for a practical hydrogen output flow rate. The energy saving in this system is that the proportion of power supplied to the cells that heat up (voltage × current) is [1 - (1.481 / V cell)]It can be shown that it can be equal to. A practical electrolytic cell can operate at 1.8 V. As a result, [1 - (1.481 / 1.8)] = ~18% of the power is sent to the cell and converted to heat rather than hydrogen. Therefore, a practical electrolytic cell requires cooling during operation, and an efficient way to achieve this cooling could be to utilize the process water itself to cool the cell. Depending on the operating conditions of the cell, a relatively high flow rate of water may be required to ensure that the peak temperature of the cell is maintained below an acceptable threshold and that the temperature gradient within the cell is also acceptable. This flow rate can also represent a water stoichiometry much greater than 1. For example, for a cell operating at 1.8 V, releasing 18% of the input energy as heat, and operating at 2.7 W / cm 2 In a cell operating at, approximately 160 water stoichiometry may be required to maintain a temperature rise of less than 10 °C across the cell. From the above design considerations, the flow rate of water to the cell is determined by the higher of either the need for appropriate reactants or the need for appropriate temperature control.

[0012] Managing the water provided to a hydrogen electrolysis cell / stack can be a major consideration for the overall hydrogen production system. Flow rate, pressure, temperature, and composition all must be adjusted to meet the requirements of the cell / stack. A typical system includes a liquid-gas separator, heat exchanger, pump, and deionization system connected in a loop to the anode side of the cell / stack and can recirculate water at the required flow rate. As the system produces hydrogen and oxygen, 1 "stoichiometric" of water is consumed. The consumed water can be replenished by injecting 1 stoichiometric of new water into the system loop from a source of acceptable quality (e.g., demineralized water, desalinated water, or municipal water). Considering the scale of the electrolysis plant, the required water flow consumed by the cell / stack can be proportional to the plant capacity. Regardless of scale, it may be desirable to keep other process parameters (pressure, temperature, composition) uniform, as this can significantly simplify the selection of system components, overall system control, and the costs of engineering, procurement, and construction (EPC) at the deployment site. For example, water pumps are generally commercially available in a wide range of scales for a given pressure capacity. Thus, it can be advantageous to have a basic cell / stack where the water flow resistance does not depend on the size of the cell or stack. Then, a larger system can be constructed modularly from more cells and / or more stacks, without the need to change the water pump technology and basic pressure rating for the system and plant.

Brief Description of the Drawings

[0013] The accompanying drawings are incorporated herein and constitute a part of this specification. The drawings illustrate only specific embodiments of the present disclosure and, together with the above and following descriptions, explain the principles of the present disclosure. As far as possible, the same identification numbers are used to indicate common or similar components across different figures.

[0014] [Figure 1]Figure 1 shows an isometric view of the electrolytic cell components of Figure 3, illustrating the exemplary intersecting flow orientation of the process fluid along the x and y axes, as well as the iteration of the cell components along the z axis to form a stack of cells.

[0015] [Figure 2] Figure 2 shows a cross-section of the electrolytic cell components in the active region of a typical cell, illustrating the flow of ions, electrons, and fluids for proton and anion exchange membrane electrolysis technology.

[0016] [Figure 3] Figure 3 shows an isometric view of the anode flow field components and illustrates the trade-offs that exist when expanding or contracting the cell active region.

[0017] [Figure 4] Figure 4 shows the mathematical model output for pressure loss versus velocity, and an illustrative pressure loss target threshold, through exemplary flow fields for water and hydrogen flows.

[0018] [Figure 5] Figure 5 shows the test results for water flow resistance for various flow field candidates, confirms the model results for water flow pressure loss in Figure 4, and explains an alternative graphical target threshold for pressure loss.

[0019] [Figure 6] Figure 6 shows the mathematical model output for water temperature rise versus water stoichiometric value with respect to the operating voltage values ​​and graphical water temperature rise threshold of two exemplary cells.

[0020] [Figure 7] Figure 7 shows the mathematical model output for the oxygen volume fraction versus water stoichiometric value at the outlet, with respect to exemplary cell operating pressure and an illustrative oxygen volume fraction threshold.

[0021] [Figure 8]Figure 8 shows multiple test results for the mechanical strength of candidate flow fields and illustrates the percentage of initial thickness the material must be calendered to withstand the target compressive load when assembled into a complete cell / stack.

[0022] [Figure 9] Figure 9 shows the basic steps that may be included in a rapid manufacturing process for creating expandable and contractible reinforced electrodes and integrated electrode flow field components.

[0023] [Figure 10] Figure 10 shows a plan view of the process in Figure 9 and illustrates the inherent y-axis expandability (l) of the reinforced electrode and flow field component manufacturing method for achieving a variable active region cell from a fixed x-axis roll web width (w).

[0024] [Figure 11] Figure 11 shows several illustrative examples of embossing or patterning the surface of electrodes and / or flow field substrates to promote bonding during lamination.

[0025] [Figure 12] Figure 12 shows a typical scanning electron microscope image of an anode electrode synthesized using the pore-forming agent disclosed herein.

[0026] [Figure 13] Figure 13 shows performance data measured over time for a preferred embodiment of the present invention, illustrating the superior lifespan compared to the prior art. [Modes for carrying out the invention]

[0027] Detailed description of a specific embodiment In one embodiment, the application provides an embodiment of a pretreatment process for creating a reinforced electrode and preventing delamination by using an adhesion promoter / primer to increase the adhesion of a catalyst ink on a substrate. Where the adhesion promoter and primer are discussed in the application, embodiments including one shall, where technically possible, provide the other alternatively or include both in combination. In some embodiments, the reinforced substrate is treated with an adhesion promoter to improve the surface adhesion of the catalyst ink. These adhesion promoters may include one or more self-assembled monolayers of aliphatic phosphonic acids, silanes, alkylthiols, or similar materials. The adhesion promoter may also include conductive adhesives, e.g., Electrodagu: Bonderite S-FN EB012 Acheson, Henkel's Loctite®, or similar materials. In some embodiments, the surface roughness of the electrode reinforcement may be modified by treatment with a surface tension altering agent, such as a surfactant (anionic, cationic, or amphoteric surfactant) containing 3M fluorosurfactant FC-4430 or similar materials. The adhesion promoter may be in liquid form, may be directly coated onto the substrate, or may be deposited using chemical vapor deposition techniques.

[0028] This application also provides embodiments for improving coating uniformity and electrode integrity by including a binder in the electrode ink recipe. The electrode ink may include one or more nonionic polymer binders, such as PTFE, PVA, PAA, PVDF, SBR, SEBS, or similar materials. The electrode ink may include an ionic polymer binder containing cationic protons or anionic hydroxide ions. The electrode ink layer may contain surface tension modifiers, such as surfactants, fluorosurfactants, silicone surfactants, siloxanes, or similar materials. Quaternized polyvinyl alcohol can be used as an additive binder. The electrode ink layer may also contain adhesion promoters, such as epoxy.

[0029] This application also provides embodiments for which a porosity-forming agent is incorporated into the electrode ink to promote pore formation, thereby providing an efficient pathway for water to reach the active reaction site of the electrode and allowing generated gases to easily escape from the active reaction site throughout the electrode. The electrode ink may contain a porosity-forming agent that promotes pore formation in the final strengthened electrode layer. The formed pores can reduce restrictions on mass transport and promote effective bubble removal in the area-expandable and strengthened anode electrode of the present invention. The porosity-forming agent may include one or more of ammonium bicarbonate, ammonium carbonate, sodium carbonate, sodium bicarbonate, or similar materials. The porosity-forming agent may include one or more leavening agents such as air, water vapor, yeast, baking soda, baking powder, poly(methyl methacrylate), wheat particles, poppy seeds, sawdust, carbon fiber, graphite, or similar materials.

[0030] In a preferred embodiment, the porosity-forming agent may include ammonium bicarbonate.

[0031] This application also provides embodiments in which electrodes may be grown directly on a reinforcing layer by processing procedures such as hydrothermal deposition, electrodeposition, indoor temperature deposition, or similar processes. The electrode layer may contain one or more of the following materials: platinum, molybdenum, nickel, cobalt, boron, cerium, iron, tin, sulfur, phosphorus, fluorine, oxygen, hydroxide, or similar materials. The electrodes may be supported on a conductive support such as carbon (Vulcan, Ketjenblack, etc.), nickel, iron, titanium, stainless steel, or a combination of these materials. In a preferred embodiment, the electrode contains iron and nickel in oxide form (NiFe2O4) using a nickel foam or nickel felt reinforcing substrate. In another preferred embodiment, the electrode contains Pt and carbon using a nickel foam, nickel felt, or carbon fiber reinforcing layer.

[0032] More specifically, metal foams, felts, sintered components, or other porous metal substrates can be functionalized to function as electrodes for water electrolyzers and / or fuel cells. These functionalized electrodes enable desired electrochemical reactions in fuel cell electrolyzers to proceed at high speed and efficiency by allowing for superior reaction dynamics due to their inherent catalytic activity and excellent conductivity for fluids, electrons, and ions.

[0033] In certain embodiments of this disclosure, the effective electrochemically active surface area ("ECSA") of the porous substrate is increased, providing more reaction sites compared to the unmodified substrate, and thus increasing system performance. In certain embodiments, this is achieved by subjecting the porous (or non-porous) substrate to an alloying step, where the added or alloyed material reacts with the surface of the porous substrate and deposits thereon, resulting in a mixture of the substrate atoms and the added material in the surface region. This is then followed by a dealloying step, where the added or alloyed material is removed again. In one example, this can be achieved by alloying (zinc plating) stainless steel or nickel with zinc in a liquid zinc bath for several seconds to several hours, and then removing the zinc in a potassium hydroxide bath or another medium that dissolves zinc from the alloy. Here, the porous substrate is characterized by a high degree of surface roughness due to nanoscale and microscale grooves and voids left by the added and subsequently removed material, corresponding to a high effective ECSA. Based on the above, those skilled in the art will understand that other alloying / dealloying steps are possible depending on the selection of the base material and alloying material, and this application is intended to encompass such other base materials and alloying materials.

[0034] In other embodiments, an increase in ECSA can be achieved by depositing or electrodepositing a material onto a substrate without subsequent removal. In other embodiments, an increase in ECSA can be achieved by depositing or electrodepositing a material onto a substrate, followed by a heat treatment to induce alloying in the material, followed by a dealloying step.

[0035] In certain embodiments of this application, additional materials (such as Pt, Ir, Ni, Fe, Mo, and other materials) are optionally deposited on the high ECSA porous substrate described in the preceding paragraph. These materials are catalytically active for the desired reaction, either intrinsically or due to interactions with the substrate material, changes occurring depending on the reaction conditions in the electrolytic and / or fuel cell, or for other reasons. In other embodiments, the additional materials are not deposited on the high ECSA porous substrate but are introduced in ionic form into the working fluid of the electrolytic or fuel cell, and therefore, surface deposition related to the concentration of the additional material in the solution determines the surface concentration.

[0036] This application also provides embodiments in which ionomers may be used in electrode ink formulations. The ionomer may include a polymer based on poly(arylpiperidinium) consisting of either piperidone monomer or 3-oxo-6-azoniaspiro[5,5]undecane salt monomer, an aromatic, and optionally a trifluoroacetophenone monomer group. The ionomer may also include an ionomer or polymer based on styrene-butadiene block copolymer (SEBS) having a quaternary ammonium group anchored via an aromatic ring. The ionomer may include a multiblock copolymer comprising one or more norbornene-based hydrophilic blocks and one or more norbornene-based or alkene-based hydrophobic blocks. The ionomer may include a trimethyl or benzyltrimethylammonium functionalized polystyrene ionomer containing different molar percentages of quaternized benzylammonium. The ionomer may also include hexamethyltrimethylammonium functionalized Diels-Alder polyphenylene (HTMA-DAPP). Ionomers may include ionomers that use tetrakis(dialkylamino)phosphonium cations as functional groups. Ionomers may include polyethylene-based triblock copolymers, polychloromethylstyrene-b-polyethylene-b-polychloromethylstyrene (PCMS-b-PE-b-PCMS) quaternized with any of the following cations: trimethylammonium or methylpiperidinium. Ionomers may include ionomers or polymers that contain cationic benzimidazolium or imidazolium-containing moieties. Ionomers may include ionomers based on hexamethyl-p-terphenylpoly(benzimidazolium). Ionomers may include ionomers or polymers having a 3M-PFSA(EW798) precursor containing a copolymer of tetrafluoroethylene (PTFE) and trifluoroethylene functionalized with a perfluorosulfonylfluoride carbon chain. The ionomer may include PPN (polyphenylene) ionomer and / or PAP (polyarylpiperidinium) ionomer.

[0037] In a preferred embodiment, the electrode ink comprises a polymer based on poly(arylpiperidinium) consisting of either a piperidone monomer or a 3-oxo-6-azoniaspiro[5,5]undecane salt monomer, an aromatic, and optionally a trifluoroacetophenone monomer group.

[0038] In another preferred embodiment, the electrode ink comprises a copolymer comprising one or more norbornene-based hydrophilic monomers and one or more norbornene-based or alkene-based hydrophobic monomers. The polymer can be a block copolymer as well as a random copolymer.

[0039] In another preferred embodiment, the electrode ink comprises a polymer based on a styrene-butadiene block copolymer (SEBS) having a quaternary ammonium group tethered via an aromatic ring.

[0040] The present invention provides embodiments in which a catalytic material is used in an electrode formulation. The anode catalytic substance is RuO2, IrO2, a spinel oxide, such as Al 0.5 Mn 2.5 O4, PbRuO x 、Fe x Ni y OOH, IrRuO2, a perovskite, Mo (direct deposition), MoP, IrO x / NbO x 、IrRuO2 / NbO x 、NiFeCo, NiCe@NiFe / NF, Fe-CoP / NF, Co3O4, Co2O3, Fe 0.33 Co 0.66 P, Fe(PO3)2 / Ni2P, (Ni,Fe)OOH, Ni-Fe-OH@Ni3S2 / NF, Ni(Fe)O x H y 、Ni x Fe y 、Ni y Fe (1-y) O x 、Co x Fe 3-xThe catalyst material may contain one or more O4 / CFP compounds, where x is (0, 0.1, ..., 2.0, 2.1, ...) and y is (0, 0.1, ..., 2.0, 2.1, ...). These catalyst materials may be in the form of nanoparticles or nanowires, which may or may not be supported on a conductive support. In some embodiments, the anode catalyst may include a catalyst accelerator such as cerium oxide or a similar material. The cathode catalyst material may be Ni x Mo y , Pt / C, Pt alloy / ECS, Pt / ECS, Pt black, Pt alloy, Ni alloy, NiZn, NiMo, MoS2 / Ni3S2 / NF, a-MoS x / CC, Co-Co2P@NPC / rGO, Ni 2(1-x) Mo 2x P / NF, Co 2.90 B 0.73 P 0.27 The catalysts may include one or more of the following: / NF, F-Co2P / Fe2P / IF, Ni2P / NF, CoP / Ni5P4 / CoP, P-Fe3O4 / IF, and A-NiCo LDH / NF, where ECS stands for engineered catalyst support. These catalyst materials may be in the form of nanoparticles or nanowires, which may or may not be supported on a conductive support.

[0041] Please understand that both the general description above and the detailed description below are illustrative and descriptive only and do not limit the disclosure as described in the claims.

[0042] In yet another embodiment of the present disclosure, the expandable electrode, regardless of the selected active region, has substantially equal resistance to the water flow, equal temperature rise, and equal outlet oxygen fraction at a given operating voltage. Preferred embodiments of the disclosed electrode may be substantially rectangular and are characterized by dimensions along the x-axis, selected based on the roll web width(w) of the electrode reinforcement and / or flow field material used in its manufacture. The desired roll web width(w) can be selected based on maintaining process parameters for the working electrode within target thresholds. For example, it may be desirable to keep the water pressure drop through the electrode below the pumping pressure limits of the system, stack, and cell in which the electrode may be installed. Alternatively, it may be desirable to maintain a water flow temperature rise below the limits of the temperature gradient of the stack, cell, or electrode to ensure acceptable performance and life. Alternatively, it may be desirable to keep the electrode outlet oxygen volume fraction below the limit to ensure stable performance and life of the cell. Alternatively, the desired roll web width(w) may be selected based on the available raw materials for constructing the electrode reinforcement. For example, it may be desirable to select a roll web width(w) that minimizes waste when converting the roll into parts during assembly. In this case, the desired roll web widths (w) for the electrodes and flow fields may be the same or different. If they are different, the selected roll web widths (w) may be chosen based on the most expensive of the electrode reinforcement or flow field, and other material rolls may be selected with a web width (w) that matches the first one, where this match means a roll web width (w) that optimizes the manufacturing speed and / or overall cost.

[0043] A variable active region can be achieved from the expandable electrode of this disclosure by adjusting the length of the anode electrode along the y-axis. Water can then be distributed parallel to the y-axis along the leading edge of the anode flow field adjacent to the electrode, using manifolds, distribution windows, plenums, and / or other features within the cell. The leading edge of the anode flow field can be defined as the edge into which water flows. The length of the anode flow field along the y-axis can be selected to keep the water velocity along the x-axis at the leading edge of the anode flow field below a predetermined threshold. The total length of the electrode along the y-axis can then determine the electrode active region and can be selected to achieve an overall target hydrogen production rate for the cell. The y-axis dimensions and flow field thickness can then be selected to keep the water flow pressure loss, water temperature rise, and / or oxygen outlet volume fraction below target thresholds.

[0044] The expandable electrode of this disclosure may include one or more electrode reinforcing substrates having a desired roll web width along the x-axis, which can be selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit. The one or more flow field substrates having a desired roll web width along the x-axis can be selected from one or more of foam, felt, woven screen, expanded metal, and sintered metal frit. The expandable electrode may also include an active electrode material coated, printed, or otherwise attached on the electrode reinforcing substrate. The expandable electrode may also include the conversion of the electrode reinforcing substrate into the active electrode material by a chemical, physical, or thermal process.

[0045] In another embodiment, a method for manufacturing an area-expandable reinforced electrode is described. An electrode reinforcement substrate with a desired roll web width along the x-axis can be selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit. Electrode reinforcement substrate material from one or more rolls can be oriented along the y-axis through calendering rollers configured to achieve a desired thickness and / or surface properties on each side of the electrode reinforcement substrate and / or to laminate multiple layers together. For example, calendering rollers positioned on each side of the substrate web may have the same or different diameters, or they may be made of the same or different materials. It may be advantageous to use a harder and / or smaller roll on the side of the electrode reinforcement substrate to be converted into the active electrode to achieve a higher density and / or smoother surface for conversion. Alternatively, it may be advantageous to use a softer and / or larger roll on the side of the electrode reinforcement substrate to be laminated onto the flow field substrate to maintain a more porous and / or rougher surface for lamination.

[0046] The electrode reinforcement substrate may be converted into an active electrode by appropriate processing. For example, the electrode material may be spray coated, screen printed, rotary screen printed, doctor blade coated, slot die coated, curtain coated, squeegee coated, or laminated onto a suitable surface of the electrode reinforcement substrate using heat and / or pressure. The electrode conversion process may also include post-coating steps. For example, the coating may be dried, heat treated, annealed, or otherwise physically or chemically treated to facilitate bonding to the substrate and / or the functional performance of the electrode.

[0047] The flow field substrate with a desired roll web width along the x-axis can be selected from the group consisting of foam, felt, woven screen, expanded metal, sintered metal frit, and combinations thereof. The flow field substrate material from one or more rolls can be oriented along the y-axis through calendering rollers configured to achieve a desired thickness, relative density, strength, and / or surface properties of the flow field and / or to laminate multiple layers of the substrate together. For example, the calendering rollers positioned on each side of the substrate web may have the same or different diameters, and may be made of the same or different materials. It may also be advantageous to use a softer and / or larger roll on the side of the flow field substrate that is to be laminated onto the electrode-reinforced substrate to maintain a more porous and / or rougher surface for lamination.

[0048] These flow fields are typically referred to as porous transport layers or gas diffusion layers. In certain embodiments of this disclosure, they are made from titanium, aluminum, carbon (e.g., carbon paper, carbon fiber composites, graphite felt, graphene, carbon cloth, etc.), nickel, copper, zinc, stainless steel (e.g., SS304, SS316, SS316L, SS430, SSA-286, etc.), other materials, or combinations thereof. They may be coated or uncoated, wet-proof (to increase their hydrophobicity), or contain a microporous layer (to improve water repellency and catalyst adhesion). In some embodiments, the gas diffusion layer has a nanostructure or microstructure. In some embodiments, the gas diffusion layer is formed of nanowires, microfibers, or cloth. Those skilled in the art will understand that the embodiments of this application can be combined so that they are used together. Further objects, features, and advantages of this application will become apparent from the detailed description of preferred embodiments set forth below, when considered together with the drawings.

[0049] Detailed description of the drawing A detailed description of the drawings is given here with reference to the attached drawings. The following description relates primarily to electrolysis, but it will be understood by those skilled in the art that the described features, components and methods are applicable and adaptable to other electrochemical technologies, including hydrogen compressors, hydrogen purifiers, CO2 electrolyticators, chlorine electrolyticators, etc. Those skilled in the art will understand that the subject matter described in the embodiments above (for example, relating to approaches for increasing the adhesion of catalyst inks to substrates, using binders in electrode inks to improve coating uniformity, incorporating porosity-forming agents into electrode inks, approaches for growing electrodes on reinforcing layers, increasing the electrochemically active surface area, and incorporating certain materials in electrode inks) may be applied to the embodiments shown in the drawings.

[0050] Figure 1 shows an isometric view of the electrolytic cell (101) illustrating the exemplary intersecting flow orientations (103) and (104) of the process fluid, as well as the repetition of cell components (105) along the z-axis (102) to form a stack of cells. Here, it can be seen that the bipolar plate (106) separates one cell of thickness (107) from the adjacent cell (105). Water and oxygen (103) can flow along the x-axis in a composite anode electrode flow field (111) of thickness (108). Hydrogen (104) can flow along the y-axis in a composite cathode electrode flow field (109) of thickness (110). Assuming that the cells are oriented such that a gravity vector is downward and parallel to the z-axis, it may be advantageous to place the anode on a membrane as shown in the figure to generate buoyancy and assist in moving oxygen bubbles formed on the anode electrode into the water flowing through the anode flow field on the anode electrode.

[0051] Figure 2 shows a cross-section of an exemplary core electrolytic cell component (201) in the active region of the cell, illustrating typical ion, electron, and fluid flows for proton (212) and anion (213) exchange membrane electrolysis techniques. Here, (208) is an impermeable separator, or bipolar, plate; (205) is the cathode flow field; (207) is the cathode electrode; (204) is the ion-conducting membrane; (206) is the anode electrode; and (203) is the anode flow field. When a power supply is attached to a cell having a negative electrode (209) at the bottom and a positive electrode (210) at the top, electrons (211) can flow upward through the cell. If the cell is an acidic proton-conducting type (212), positive hydronium ions can be guided to move downward through the membrane (204) by the resulting electric field. If the cell is an alkaline hydroxide conduction type (213), negative hydroxide ions can be guided to move upward through the membrane (204) by the resulting electric field. In both types, hydrogen can form on the cathode (207) and flow into the cathode flow field (205), while oxygen can form on the anode (206) and flow into the anode flow field (203). In a dry cathode system, water may be supplied only to the anode flow field (203) as a reactant to form hydrogen and oxygen. Stoichiometry is a term relating to the “balance” of a chemical reaction. In an electrochemical cell, the term “stoichiometry” or “stoichiometry” refers to the ratio of reactants supplied to the cell to the amount required to precisely balance the entire reaction. As previously stated herein, the water stoichiometry supplied to the anode flow field (203) may be much higher than 1. Furthermore, since the fluid in the anode flow field (203) can be almost liquid, this section may exhibit significantly greater flow resistance compared to the cathode flow field. The thickness of the cathode flow field (214) and the anode flow field (215) can affect the flow velocity, temperature distribution, and pressure loss within the cell. The overall cell pitch (216) of the cell can be determined by the thickness of each of the components (203) to (208) that make up the complete cell.A small cell pitch (216) may be desirable to produce electrolytic cell stacks with high power density and small size for a given hydrogen production rate [kg / hr]. Therefore, optimizing the geometric shape of the anode flow field (length along the x-axis in the direction of water flow, width along the y-axis, and thickness along the z-axis) can be an important design goal for the electrolytic cell. For example, the flow fields of the anode (203) and / or cathode (205) may consist of thicknesses of 0.1–5.0 mm, 0.2–3.0 mm, 0.3–2 mm, 0.5–2 mm, or 0.6–2 mm. The flow fields (203) and (205) may be selected with the same or different thicknesses based on factors for optimizing cell process conditions, performance, and manufacturing.

[0052] Figure 3 shows an isometric view (301) of the anode electrode flow field component (306) illustrating the trade-offs that may exist when expanding or contracting the cell area. The anode flow field can have a width "w" (305) along the x-axis, a length "l" (304) along the y-axis, and a thickness "t" (303) along the z-axis. The width "w" (305) along the x-axis can be 5-1000 cm, 5-500 cm, 5-100 cm, or 10-50 cm. The length "l" (304) along the y-axis can be 1-5000 cm, 5-3000 cm, 10-1000 cm, or 25-1000 cm. The active region (307) can be found by multiplying the width "w" (305) by the length "l" (304). The water flow area at the leading edge (308) can be found by multiplying the thickness "t" (303) by the length "l" (304). The water flow for fixed stoichiometry and efficiency (309) into this water flow region (308) can be determined by region (307). To achieve higher hydrogen production [kg / hr] with fixed efficiency and water stoichiometry, additional areas "dA" (311a) and / or (311b) may be required. If "dA" (311b) is created by adding "dw" (310b) to "w" (305), then additional water (313b) may be required to flow into the flow region (308) at the fixed leading edge. The added water flow can thereby increase the water velocity through the flow field and result in an increase in pressure drop (314). If "dA" (311a) is created by adding "dl" (310a) to "l" (304), the additional water (313a) may be accompanied by a proportional increase in the flow area (312a) of the fixed leading edge. The added water can flow through the incremental proportional flow region (312a) without increasing the pressure drop (314). Thus, expanding or contracting the area along the y-axis may allow all process conditions, such as pressure, temperature, and oxygen volume fraction within the electrode, to remain constant. The total water flow rate may necessarily be proportional to the hydrogen / oxygen production rate, while other system parameters may remain constant by expanding or contracting the electrode only along the y-axis. This can greatly simplify the resulting electrolytic system made from electrodes designed in this way.For example, specifications for an electrolytic cell manufacturing plant, including pressure ratings, temperature ratings, and / or fluid composition ratings, can be consistent across plants with different water flow and hydrogen / oxygen capacities. This, in turn, simplifies engineering procurement and construction activities, expands the available supply of system components, and reduces overall hydrogen production costs.

[0053] Figure 4 shows mathematical model results (431) for pressure loss per unit flow length (414) [mbar / cm] as a function of flow velocity (409) [cm / s] for hydrogen gas (432) and liquid water (433) flowing through typical porous media that can be used in anode and / or cathode flow fields. Also shown are illustrative target pressure loss thresholds (434) that can be selected based on the overall electrolytic stack and system design. The threshold (434) represents an upper limit on water pressure loss, thereby allowing the definition of a target threshold for water velocity in the anode flow field (435). As is evident from the results (431), the pressure loss per unit length for hydrogen can be several times smaller than that for water at a given velocity. Therefore, as the cell area increases, it may be advantageous to prioritize the expansion or contraction of the electrodes based on the water velocity and flow length. For example, a water pump for supplying water to an electrolytic cell may have a pressure capacity of up to 10 bar. It may be advantageous to configure the anode flow field (401) such that water velocities (409) less than 100 cm / s, less than 50 cm / s, less than 20 cm / s, less than 10 cm / s, or less than 5 cm / s remain within the capacity of commonly available system water pumps.

[0054] Figure 5 shows test results (561) for pressure loss per unit flow length (514) [mbar / cm] as a function of flow velocity (509) [cm / s] for liquid water flowing through several porous medium candidates that may be used in anode and / or cathode flow fields. The mathematical model results from Figure 4 (533) are repeated for reference, along with a graphical target pressure loss threshold (534) that may be selected based on the overall electrolytic stack and system design. The threshold (534) can represent an upper limit on water pressure loss and thereby defines a target threshold for water velocity in the anode flow field (535) for these actual potential flow field candidates (samples 1-8).

[0055] Figure 6 shows the mathematical model result (641) for the water temperature rise (615) [°C] as a function of the stoichiometric value of the supplied water. The heat released during electrolytic cell operation may be a function of efficiency, which may then be a function of the operating cell voltage. Saving energy for the cell may result in an equation for the water temperature rise, as specified in equation 6c-1 (below), where V is the cell voltage, V0 is the thermal neutral cell voltage [1.25V], LHV is the low heating value of hydrogen [120MJ / kg], c p is the specific heat of water [4.182 kJ / kg°C], and St is the stoichiometric value of the water supplied to the cell. Plots (642) and (643) show the results of this model at two possible operating voltages representing exemplary values ​​for the start [BoL] and end [EoL] of the electrolytic cell's life. Also shown is an illustrative target water temperature rise threshold (644), beyond which the anode electrode may not operate stably or enduringly, or beyond which the electrolytic cell, stack, or system may not operate efficiently. The temperature rise threshold can be used in conjunction with the EoL voltage limit to define a lower limit threshold (645) for the water stoichiometric value. It may be advantageous to select the water stoichiometric value to maintain the water temperature rise at the end of life below 100°C, below 50°C, below 25°C, below 15°C, or below 10°C to maintain stable and enduring operation of the electrode.

[0056] Formula 6c-1:

number

[0057] Figure 7 shows the mathematical model result (751) for the oxygen volume fraction at the anode flow field outlet (752) as a function of the stoichiometric value of the supplied water. The electrolytic process splits the water into hydrogen on the cathode side and oxygen on the anode side. Once oxygen is formed on the anode, it can mix as a gas with the dispensed liquid water, resulting in a two-phase flow in the anode flow field. The oxygen volume fraction at the anode outlet may indicate the operational stability, performance, and / or durability of the electrode, and a target threshold for this parameter can be set by the designer. Conserving mass for the cell can lead to an equation for the oxygen outlet volume fraction, such as that specified in equation 7d-1, where r O2 is the density of oxygen gas at the anode outlet, and r H2O is the density of liquid water at the anode outlet, and St is the stoichiometry of the water supplied to the cell. Plot (752), along with an illustrative oxygen volume fraction threshold (754), shows the results of this model at a pressure of 10 bara at the anode electrode, above which the electrode may not operate stably or enduranceously, or above which the electrolytic cell, stack, or system may not operate efficiently. The oxygen volume fraction threshold can be used to determine a lower threshold (755) for water stoichiometry. To maintain stable and endurance operation of the electrode, it may be advantageous to select water stoichiometry to maintain the oxygen volume fraction below 80%, below 60%, below 50%, below 40%, or below 30%.

[0058] Formula 7d-1:

number

[0059] Figure 8 shows measured strength data (861) for several samples of candidate electrode reinforcement materials, illustrating the permanent change in thickness (809) as a function of mechanical exposure stress (814). This curve represents the material bending strength as a function of deformed thickness. During the assembly of the electrolytic stack, a compressive load is applied to the active region to maintain sufficient contact and low contact resistance between layers within the cell and between individual cells within the stack. The compressive load applied during assembly may be greater than the expected internal fluid pressure of the stack to ensure that the cells or cell components do not separate during operation. To ensure that this contact is maintained, it is desirable to maintain the elastic behavior of the cells and cell components. As indicated by limits (834) and (835), it may be advantageous to permanently deform the electrode reinforcement to a value less than X% of their initial thickness to ensure that the electrode reinforcement remains elastic. For the tested candidate materials, x = 40%, however, the specific value for any candidate electrode reinforcement material may be greater than or less than 40%, based on the specific properties and material characteristics of that candidate, including porosity, basis weight (defined as mass per unit area in the xy plane), structural material, and porous shape (e.g., foam, mesh, expanded metal, felt, or others).

[0060] Figure 9 shows the basic steps in a rapid manufacturing process (901) for producing reinforced electrodes and flow field components (913). One or more rolls of porous substrate (903a) can be selected based on a desired roll web width "w" (915), as previously described. The substrate may include foam, felt, woven screen, expanded metal, sintered frit, or fiber cloth or paper. The selected substrate may have a porosity up to 98%, where porosity is defined as the volume percentage of the substrate available for fluid flow. For example, the porosity may be 98%-40%, 95%-50%, 90%-60%, or 95%-80%. The composition of the substrate may include iron, nickel, chromium, steel, stainless steel, Inconel, aluminum, titanium, carbon, or combinations thereof. The substrate may be plated or coated with other materials, such as platinum, gold, tin, carbon, titanium nitride, PTFE, or another corrosion-inhibiting layer (including a processed layer of a polymer or oxide material having a conductive metal or carbon pathway). The roll (903a) may be loaded onto an unwinding station designed to hold the web flat under known surface tension and to be able to move along the y-axis (902). The roll (903a) may be calendered through a pair of rollers (904) and (905) to laminate two or more layers together, thereby reducing the porosity of the web, reducing or increasing its thickness, increasing its strength, increasing its stiffness, and / or creating desired surface properties on one or both sides of the web (906). For example, it may be advantageous for the substrate to have one side relatively smooth and the other side rough to facilitate later steps in the process. It may also be advantageous to achieve a porosity gradient through the thickness of the substrate. For example, it may be beneficial for downstream processes if one side (906) of a calendered substrate has relatively low porosity to accept conversion to an electrode, while the opposite side of (906) has relatively high porosity to facilitate bonding with a second substrate.To achieve different properties on each side of the web (906), the rollers (904) and (905) may have the same or different diameters, and / or be made of the same or different materials, and / or be constructed with different surface finishes or coatings, and / or provide a specific surface pattern which may be embossed on one or both sides of the roll web (903a). The calendered reinforcing substrate (906) may then be converted into an electrode (908) in a method (907) as described in embodiments of the present disclosure. For example, the electrode material may be laminated on a suitable surface of the electrode substrate (906) using heat and / or pressure by spray coating, screen printing, rotary screen printing, doctor blade coating, slot die coating, curtain coating, squeegee coating, or as a film, decal or solid layer. The electrode conversion process (907) may also include post-coating steps. For example, the coating may be dried, heat-treated, annealed, and / or otherwise physically or chemically treated to facilitate bonding to the substrate and / or the electrochemical performance of the cell. The conversion process (907) may also include a chemical or physical vapor deposition process for conversion to an active electrode (908). The conversion process (907) may also include a plasma or flame spray process (906) for depositing or chemically reacting and / or converting the electrode material onto the substrate (906). Following process (907), the electrode web (908) may be positioned adjacent to one or more additional rolls of porous substrate (903b). These substrates may be identical or different to the electrode substrate (903a) and may be selected based on a similar range of possible materials and properties as (903a), but to satisfy functional requirements for a fluid flow field rather than electrode reinforcement. For example, making (903b) identical to (903a) may result in the highest purchase volume and lowest supply cost. Selecting (903b) from a different substrate than (903a) may be advantageous for battery performance (electrical resistance, fluid resistance, thermal conductivity, mechanical elasticity, or mechanical strength).In process step (910), the electrode web (908) may be laminated onto the flow field web (909) by a suitable lamination process. The lamination process (910) may include mechanical rolling or calendering through rollers similar to (904) and (905) to facilitate the simultaneous penetration of solid fibers, interlayers, or wires from the web (908) to the web (909). To achieve this mechanical bonding, the similar rollers (904) and (905) may have the same or different diameters, and / or be made of the same or different materials, and / or consist of different surface finishes or coatings, and / or have specific surface patterns. Although (903a) and (903b) are selected from the same supply material, it may be advantageous to pre-calender and / or laminate multiple layers of (903b) before the lamination step (910). The pre-calendering / lamination step may include embossing a pattern on the (909) side that is co-penetrated with (908) to facilitate mechanical bonding. The lamination process (910) may also include other steps, including heat treatment or application of bonding promoters such as adhesives, polymer suspensions, liquid ionomers, or ionomer suspensions to one or more of the webs (908) and (909). The order of steps (907) and (910) may be reversed so that the conversion of the web (906) to the electrode (908) may occur after lamination to the web (909). Certain electrode materials and / or methods may be advantageous to be formed only after calendering and lamination to ensure that proper adhesion is maintained within the final web (911). In some cases, the electrodes may be coated on a film, in which case the conversion step (907) may be omitted in process (901). Following the lamination step (910), the unitized electrode flow field web (911) may be processed to produce individual parts (913) of appropriate size for integration into an electrolytic cell (915) (912). For example, the web (911) can be processed in step (912) by punching it out with a knife or other cutting die to ensure accurate sizing of the part pieces.In some cases, lamination of web (908) onto web (909) can be performed after the cutting step (912). The exact size of the part (913) may depend on whether an anode electrode flow field or a cathode electrode flow field is to be generated. The overall process (901) may be adapted to generate either an anode electrode / flow field or a cathode electrode / flow field as needed, and the specific materials, coatings, steps, and settings of the line may be the same or different for each. In manufacturing, to enable high-speed production of complete electrolytic cells, one anode electrode / flow field and one cathode electrode / flow field can be manufactured simultaneously by using two independent lines.

[0061] Figure 10 shows a plan view (xy plane) of the process described in Figure 9. The descriptive labels are kept consistent across the drawings. The area scalability of the present invention is demonstrated by a variable-length die cutting step (912) which yields a variable-area electrode component piece (913) by changing only the length (1009) of the component. The process (901), as described in Figures 3-7, has the advantage that the capital equipment required to manufacture electrodes with varying active areas is a roll with a fixed handling width (915), while achieving consistent operating conditions for electrodes of various sizes.

[0062] Figure 11 shows several illustrative examples of patterning or embossing of electrode and / or flow field substrates to facilitate enhanced bonding between lamination steps of process (901). Patterns may be linear along the y-axis, along the x-axis (not shown), or along both the x-axis and y-axis in cross-hatch styles (1123) and (1124), as shown in (1121) and (1122). The depth and spacing of the profile shapes (triangle (1121), rectangle (1122), or other shapes (not shown)) may be optimized based on the material and other properties of the substrates being laminated.

[0063] Figure 12 shows an electron scanning microscope image of an electrode synthesized according to a preferred embodiment of the present invention using a bicarbonate pore-forming agent, illustrating the macroscopic and microscopic porosity of the obtained electrode structure.

[0064] Figure 13 shows 0.5 A / cm 2 Performance data (1301) of cell voltage (1304) as a function of operating time (1305), measured on a cell operating at 60°C, using a NiFe2O4 anode electrode synthesized and manufactured on a nickel foam reinforced layer according to a preferred embodiment of the present invention. The data shows endurance operation exceeding 330 hours without catalyst separation or efflux. For comparison, published data (1302) [ACS Appl.Mater.Interfaces 2021,13,44,51917-51924,https: / / pubs.acs.org / doi / 10.1021 / acsami.1c06053] was superimposed, showing greater decay rates and inferior lifetimes for three competing systems (1303) under comparable operating conditions compared to the present invention (1301).

[0065] Further embodiments: A-1. active electrode material, Reinforcement base material, and An electrode for an electrochemical cell, including a flow field, The open flow field includes a material selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit, and includes a first layer having a desired roll web width along the x-axis. The reinforcing base material comprises a material selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit, and includes a second layer having a desired roll web width along the x-axis. The thickness of the flow field along the z-axis and the length of the flow field along the y-axis are independently adjustable, generating a variable cell active region that maintains water flow resistance, water temperature rise, or cell outlet oxygen volume fraction below a target threshold for the electrode. A-2. The thickness and length are selected to achieve a water flow velocity of less than 100 cm / s at the leading edge of the flow field, or the thickness and length are selected to achieve a water flow pressure drop of less than 5 bar between the leading edge and the training edge of the flow field when operating under rated conditions and hydrogen generation capacity. The electrode described in A-1. A-3. The open flow field includes multilayer laminates. The electrodes described in A-1 to A-2. A-4. The combined thickness of the reinforced electrode and the flow field is less than 3 mm, preferably less than 2 mm, and most preferably less than 1 mm. Electrodes A-1 to A-3. A-5. The water temperature rise is less than 50°C. The electrode according to claims A-1 to A-4. A-6. The outlet oxygen volume fraction is less than 95%. The electrode according to claims A-1 to A-5. A-7. The active electrode material is bonded to a reinforcing substrate with an adhesion promoter selected from the group consisting of adhesives, polymer dispersions, liquid ionomers, ionomer dispersions, and mixtures thereof. Electrodes as described in A-1 to A-6. A-8. The bonding accelerator is PTFE incorporated into the electrode ink during synthesis. Electrodes as described in A-1 to A-7. A-9. The active electrode material contains a foaming agent selected from the group consisting of ammonium bicarbonate, ammonium carbonate, sodium carbonate, sodium bicarbonate, air, water vapor, yeast, baking soda, baking powder, and mixtures thereof. Electrodes as described in A-1 to A-8. A-10. The active electrode material and flow field include at least one of carbon, nickel, titanium, iron, chromium, stainless steel, or Inconel. Electrodes as described in A-1 to A-9. A-11. The electrode reinforcing substrate and flow field include one or more nickel foam layers. The electrodes described in A-1 to A-10. A-12. The porosity, basis weight, number of layers, and final stacking thickness of the flow field are selected to prevent buckling during cell assembly, compression, and operation. The electrodes described in A-1 to A-11. A-13. The flexion strength achieved is 5 kgf / cm². 2 Larger, preferably 10 kgf / cm² 2 A larger, and more preferable, 15 kgf / cm² 2 Larger, and most preferably 25 kgf / cm² 2 Larger, The electrodes described in A-1 to A-12. A-14. One or more of the electrode reinforcement substrate and the flow field substrate include a rough surface, a patterned surface, or an embossed surface to facilitate lamination. The electrode according to claims A-1 to A-13. B-1. A method for manufacturing an integrated electrode flow field for an expandable and contractible electrolytic cell, Selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit, forming an open flow field through lamination or calendering of one or more layers having a desired roll web width along the x-axis and a desired thickness along the z-axis. Cutting an open flow field into individual parts corresponding to a desired length along the y-axis, An electrode reinforcement substrate is formed by laminating one or more layers having a desired roll web width along the x-axis, to a desired thickness along the z-axis, and / or calendering, selected from the group consisting of foam, felt, woven screen, expanded metal, and sintered metal frit. Converting the formed electrode reinforcement substrate into an active reinforced electrode, Cutting the active reinforced electrode web into separate parts having a desired length along the y-axis, and A method comprising arranging open flow fields and active reinforcing electrode components adjacent to each other so that the resulting assembly achieves a desired cell activity region while maintaining one or more of the following below the target threshold of the electrodes: water flow resistance, water temperature rise, or cell outlet oxygen volume fraction. B-2. The aforementioned thickness and length are selected to achieve a water flow velocity of less than 100 cm / s at the leading edge of the flow field. The method described in B-1. B-3. The aforementioned thickness and length are selected to achieve a water flow pressure drop of less than 5 bar between the leading edge and the training edge of the electrode flow field when operating under rated conditions and hydrogen generation capacity. The method described in B-1 to B-2. B-4. The combined thickness of the reinforced electrode and the flow field is less than 3 mm, preferably less than 2 mm, and most preferably less than 1 mm. The method described in B-1 to B-3. B-5. The water temperature rise is less than 50°C. The method described in B-1 to B-4. B-6. The outlet oxygen volume fraction is less than 95%. The method described in B-1 to B-5. B-7. The flow field web and reinforced electrode web are laminated before being cut into separate parts. The method described in B-1 to B-6. B-8. The electrode substrate and flow field substrate include at least one of carbon, nickel, titanium, iron, chromium, stainless steel, or Inconel. Methods B-1 to B-7. B-9. One or more of the reinforced electrode webs and flow field webs are processed to produce a rough surface, a patterned surface, or an embossed surface to facilitate lamination. The method described in B-1 to B-8. B-10. The lamination step includes a bonding promoter selected from the group consisting of adhesives, polymer dispersions, liquid ionomers, and ionomer dispersions. The method described in B-1 to B-9. B-11 The reinforcing material is 100g / m 2 and 1000g / m 2 It includes one or more nickel foam layers having a basis weight between the following: The method described in B-1 to B-10. B-12. The electrode conversion of the electrode-reinforced substrate is performed before lamination onto the flow field web. The method described in B-1 to B-11. B-13. The electrode conversion of the electrode-reinforced substrate is performed after lamination onto the flow field web. The method described in B-1 to B-12. B-14. The reinforced electrodes and flow field are stacked on the assembly within the electrolytic cell. The method described in B-1 to B-13. B-15. The porosity, basis weight, number of layers, and final stacking thickness of the flow field are selected to prevent buckling during cell assembly, compression, and operation. The method described in B-1 to B-14. B-16. The bending strength is 5 kgf / cm². 2 Larger, preferably 10 kgf / cm² 2 A larger, and more preferable, 15 kgf / cm² 2 Larger, and most preferably 25 kgf / cm² 2 Larger, The method described in B-1 to B-15. C-1. A method for increasing the effective electrochemically active surface area of ​​a substrate, The process involves alloying a substrate using an alloying material and incorporating the alloying material into the surface of the substrate. A method comprising subsequently de-alloying the substrate to remove the alloying material; or C-2. The substrate is porous. Method C-1. C-3. A method for increasing the effective electrochemically active surface area of ​​a substrate, A method comprising depositing or electrodepositing a material onto a substrate such that the added material creates a higher surface roughness. C-4. The process further includes applying heat treatment to induce alloying of the material, followed by dealloying the substrate to remove the alloying material. Methods for C-3. C-5. Further comprising depositing or electrodepositing additional catalyst material onto the substrate, Methods used in C-1 to C-4. C-6. The method further includes introducing an ionic material into the working fluid that is deposited on an electrochemically active surface area and increases the catalytic activity of the surface. Methods used in C-1 to C-5. D-1. A method for increasing the adhesion strength of a catalyst ink to a substrate, A method comprising treating a substrate with an adhesion promoter: Here, the adhesion promoter is selected from the group consisting of (a) self-assembled monolayers of aliphatic phosphonic acids, silanes, alkylthiols or similar materials, (b) conductive adhesives such as Electrodagu: Bonderite S-FN EB012 Acheson or similar materials, and (c) mixtures thereof. D-2. The method further includes modifying the surface roughness of the substrate, wherein the surface roughness is modified by treating the surface with a surface tension-altering agent, such as a surfactant containing 3M fluorosurfactant FC-4430 or a similar material. The method described in D-1. D-3. The substrate is an electrode. The methods described in D-1 to D-2. E-1. An electrode ink for coating electrodes, Electrode ink containing a binder or porosity-forming agent. E-2. The binder is selected from the group consisting of PTFE, PVA, PAA, PVDF, SBR, SEBS, and similar materials. Electrode ink as described in E-1. E-3. The binder is an ionic polymer binder containing cationic protons or anionic hydroxide ions. Electrode inks as described in E-1 to E-2. E-4. The material further comprises a surface tension altering agent, the surface tension altering agent being selected from the group consisting of surfactants, fluorosurfactants, silicone surfactants, siloxanes, and similar materials. Electrode inks as described in E-1 to E-3. E-5. Further containing quaternary polyvinyl alcohol, Electrode inks as described in E-1 to E-4. E-6. The pore-forming agent is selected from the group consisting of ammonium bicarbonate, ammonium carbonate, sodium carbonate, sodium bicarbonate, similar materials, and mixtures thereof. Electrode inks as described in E-1 to E-5. E-7. Pore-forming agents are leavening agents, and leavening agents are selected from the group consisting of air, water vapor, yeast, baking soda, baking powder, similar materials, and mixtures thereof. Electrode inks as described in E-1 to E-6. F-1. A method for manufacturing electrodes, A method for manufacturing, comprising growing electrodes on a reinforcing layer via hydrothermal deposition, electrodeposition, indoor-condition deposition, or similar processes. F-2. The electrodes include platinum, molybdenum, nickel, cobalt, boron, cerium, iron, tin, sulfur, phosphorus, fluorine, oxygen, hydroxides, similar materials, or mixtures thereof. How to perform F1. F-3. The electrodes are supported on a conductive support, which includes carbon (such as Vulcan, Ketjenblack), nickel, iron, titanium, stainless steel, or a combination of these materials. Methods used for F-1 to F-2. F-4. The electrode contains nickel iron oxide (NiFe2O4), The reinforcing layer contains nickel foam or nickel felt. Methods used for F-1 to F-3. F-5. The electrodes contain Pt and carbon. The reinforcing layer includes a nickel foam, nickel felt, or carbon fiber reinforcing layer. Methods for F-1 to F-4.

[0066] The foregoing description is provided for illustrative and illustrative purposes only. It is not intended to be exhaustive or to limit this application to the exact form disclosed, and modifications and variations are possible and / or may be apparent in light of the foregoing teachings or may be obtained from practicing this application. The embodiments have been selected and described to illustrate the principles of this application and their practical applications, and have enabled the use of this application with various modifications in various embodiments so as to be suitable for specific uses contemplated by those skilled in the art. The scope of any published patent is intended to be defined by the claims attached herein. [Explanation of symbols]

[0067] 101 Electrolyzer 102 axis 103 Water and oxygen 104 Hydrogen 105 Cell Components 106 Bipolar Plate 107, 108, 110 thickness 109 Cathode electrode flow field 111 Anode electrode flow field 203 Anode flow field 204 Ion-conducting membrane 205 Cathode Flow Field 206 Anode electrodes 207 Cathode electrode 208 Impermeable Separator 209 Negative electrode 210 Positive electrode 216 cell pitch 307 Active region 308 Water flow area

Claims

1. A method for increasing the effective electrochemically active surface area of ​​a porous substrate, To provide a porous substrate containing nickel foam or nickel felt, The porous substrate is alloyed using an alloy material, and the alloy material is incorporated into the surface of the substrate. Next, the porous substrate is de-alloyed to remove the alloy material. Depositing a material containing nickel and iron onto the porous substrate having an increased effective electrochemically active surface area, A method that includes this.

2. Further comprising depositing or electrodepositing an additional catalyst material onto the porous substrate, The method according to claim 1.

3. The method further includes introducing an ionic material into the working fluid that is deposited on an electrochemically active surface area and increases the catalytic activity of the surface. The method according to claim 1 or 2.

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